For a quick summary of the last 25 million years in human brain evolution, just watch how our brains change between infancy and adulthood.

Over its first few decades, the human cerebral cortex — the brain’s wrinkled outer tissue — evolves in ways that parallel its evolution since we last shared a common ancestor with macaque monkeys.

It’s not an absolute one-to-one correlation, but the overlap is so striking that it’s hard to ignore, said neurobiologist David Van Essen of Washington University in St. Louis.

In a study published July 12 in the Proceedings of the National Academy of Sciences, Van Essen’s team compared brain scans of infant and adult humans. The resulting differences were then mapped against a comparison of cortex shape differences in adult humans and macaques, with whom our species last shared a common ancestor 25 million years ago.